I don't know for sure, but I suspect the soduku found here are among the hardest anywhere.

Actually, CT, the puzzles here have a purposefully set difficulty limit. The are solvable with some, but not all of the more advanced solving techniques. The super hards at Brainbashers are one or two steps more difficult, and the nightmare's at Ruud's site are, well, as described (many would argue they are not solvable using logic alone - I won't argue with them, but they require, at least, advanced advanced techniques).

EDIT (9-15-06): I didn't catch the link to krazydad.com. Sorry CT.

Last edited by AZ Matt on Fri Sep 15, 2006 11:40 pm; edited 1 time in total

I don't know for sure, but I suspect the soduku found here are among the hardest anywhere.

Actually, CT, the puzzles here have a purposefully set difficulty limit. The are solvable with some, but not all of the more advanced solving techniques. The super hards at Brainbashers are one or two steps more difficult, and the nightmare's at Ruud's site are, well, as described (many would argue they are not solvable using logic alone - I won't argue with them, but they require, at least, advanced advanced techniques).

I haven't tried any of the Krazydads. But my take is that many, if not most, sites have ratings that are overstated; they may not be overstated when compared to the ratings of other puzzles on their sites, but they are overrated compared to what the words mean to me.

The Super Hards at Brain Bashers are not super hard based on how I would interpret those words. I haven't done one in a few weeks, but I don't recall that they're particularly difficult.

Similarly, the Nightmares aren't what I would think they are when I think of what the word "nightmare" means to me. They're good puzzles, not easy, they often require a number of techniques that are regularly discussed here, but "nightmare"? I don't think so.

A few months ago I tried a couple of puzzles rated "Outlaw" from Paul's Pages. They were near-impossible, as I recall. The "Tough" puzzles from www.sudoku.com/au have often been difficult for me and that might be an exception, as "Tough" might be an understatement.

I think that Ruud's puzzles are fairly described as nightmares from the average solvers point of view. I would say the next category after nightmares is "pros and extreme hobbyists only"... And I totally agree, Marty; there are a lot of good puzzles "more difficult" than nightmares out there. I just wouldn't want a casual hobbyist to jump from the very hards here to the extreme puzzles.

I don't know for sure, but I suspect the soduku found here are among the hardest anywhere.

Actually, CT, the puzzles here have a purposefully set difficulty limit. The are solvable with some, but not all of the more advanced solving techniques. The super hards at Brainbashers are one or two steps more difficult, and the nightmare's at Ruud's site are, well, as described (many would argue they are not solvable using logic alone - I won't argue with them, but they require, at least, advanced advanced techniques).

I think you might have missed the fact that the word "here" in my post was linked to krazydad.com. I didn't mean right here at dailysudoku. Sorry about that, I should've used less ambiguous wording.

All of the sites that have been mentioned in this thread have puzzles that are pretty damn challenging. I did today's Nightmare and found it easier than the highest difficulty at krazydad, but I suspect everyone has their own favorite sites when it comes to the very hardest puzzles. One thing I have noticed is that some sites' puzzles seem to have a certain "feel" to them, some intangible factor that's unique to the puzzles from that site. Presumably this is due to differences in the algorithm used to create the sudoku at that site. I'm not claiming I could identify the origin of a given puzzle with any accuracy just by looking at the grid and doing the puzzle, but maybe the idea isn't completely far-fetched. There are a great variety of sudoku out there.